To the best of my knowledge, the min and max VID is not effected by overclocking or any other bios settings. Depending on your C1E / SpeedStep settings, VID can change between those two values. The main screen of RealTemp reports the current VID, while the Settings screen shows the possible range. On a mobile chip I've spotted 4 different VID values reported as the processor transitioned from idle to full load.
The single value that CoreTemp reports only tells you part of the VID story.